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Archive for August, 2013

Our Human Origins—Part III

Evolution is the Real Story

Introduction

In this the final segment of the series (Part III) I am going to provide a summarized view of human evolution, discuss the scientific relevance of the evidence for evolution, tell my cyberspace audience how they can go about learning their own origin going back 160,000-200,000 years ago, and, finally, discuss my ancestral journey out of Africa. As you read this material be informed that Ma refers to “Millions of Years Ago” and ka refers to “Thousands of Years Ago”.

Summarized Events of Human Evolution

Hominidae

Date

Event

15 Ma Hominidae  (great apes) speciate from the ancestors of the gibbon (lesser apes).
13 Ma Hominidae  ancestor’s speciate from the ancestors of the orangutan. Pierolapitheus catalaunicus is believed to be a common ancestor of humans and the great apes or at least a species that brings us closer to a common ancestor than any previous fossil discovery. It had special adaptations for tree climbing, just as humans and other great apes do: a wide, flat rib cage, a stiff lower spine, flexible wrists, and shoulder blades that lie along its back.

10   Ma

The lineage currently represented by humans and the Pan genus (chimpanzees and bonobos) speciates from the ancestors of the gorillas.

7   Ma

Sahelanthropus tchadensis Hominina speciate from the ancestors of the chimpanzees. Both chimpanzees and humans have a larynx that repositions during the first two years of life to a spot between the pharynx and the lungs, indicating that the common ancestors have this feature; a precondition for vocalized speech in humans. The latest common ancestor lived around the time of Sahelanthropus tchadensis, ca. 7 Ma; S. tchadensis is sometimes claimed to be the last common ancestor of humans and chimpanzees, but there is no way to establish this with any certainty.  The earliest known representative from the ancestral human line post-dating  the separation with the chimpanzee lines is Orrorin tugenensis (Millennium Man, Kenya; ca. 6 Ma).

4.4   Ma

Ardipithecus is a very early hominin genus (subfamily Homininae). Two   species are described in the literature: A. ramidus, which lived about 4.4 million years ago during the early Pliocene, and A.kadabba, dated to approximately 5.6 million years ago (late Miocene). A. ramidus had a small brain, measuring between 300 and 350 cm. This is about the same size as modern bonobo and female common chimpanzee brain, but much smaller than the brain of australopithecines like Lucy (~400 to 550 cm) and slightly over a fifth the size of the modern Homo sapiens brain.Ardipithecus was arboreal, meaning it lived largely in the forest where it competed with other forest animals for food, including the contemporary ancestor for the chimpanzees. Ardipithecus was probably bipedal as evidenced by its bowl shaped pelvis, the angle of its foramen magnum and its thinner wrist bones, though its feet were still adapted for grasping rather than walking for long distances.

3.6   Ma

Australopithecus afarensis Some Australopithecus afarensis left human-like footprints on volcanic ash in Laetoli, Kenya (Northern Tanzania) which provides strong evidence of full-time bipedalism. Australopithecus afarensis lived between 3.9 and 2.9 million years ago. It is thought that   A. afarensis was ancestral to both the genus Australopithecus and the genus Homo. Compared to the modern and extinct great apes, A. afarensis has reduced canines and molars, although they are still relatively larger than in modern humans. A. afarensis also has a relatively small brain size (~380–430 cm³) and a prognathic (i.e. projecting anteriorly) face.  Australopithecines have been found in savannah environments and probably increased its diet to include meat from scavenging opportunities. An analysis of the Australopithecus africanus lower vertebrae suggests that females had changes to support bipedalism even while pregnant.

3.5   Ma

Kenyanthropus platyops, a possible ancestor of Homo, emerges from the Australopithecus genus.

3   Ma

The   bipedal australopthecines (a genus of the Hominina subtribe) evolve in the savannas of Africa being hunted by Dinofelis. Loss of body hair takes place in the period 3-2 Ma, in parallel with the development of full bipedalism.

Homo

Date

Event

2.5   Ma

Homo habilis Appearance of Homo. Homo habilis is thought to be the ancestor of the lankier and more sophisticated Homo ergaster, lived side by side with Homo erectus until at least 1.44 Ma, making it highly unlikely that Homo erectus directly evolved out of Homo habilis. The first stone tools began appearing at the beginning of the Lower Paleolithic.Further information: Homo rudolfensis

1.8   Ma

A reconstruction of Homo erectus.Homo erectus evolves in Africa. Homo erectus would bear a striking resemblance to modern humans, but had a brain about 74 percent of the size of modern man. Its forehead is less sloping than that of Homo habilis, and the teeth are smaller. Other hominid designations such as Homo georgicus, Homo ergaster, Homo pekinensis, and Homo heidelbergensis are often put under the umbrella species name of Homo erectus.Starting  with Homo georgicus, found in what is now the Republic of Georgia  dated at 1.8 Ma, the pelvis and backbone grew more human-like and gave H. georgicus the ability to cover very long distances in order to follow herds of other animals. This is the oldest fossil of a hominid found outside of Africa. Control of fire by early humans is achieved 1.5 Ma by Homo ergaster.  Homo ergaster reaches a height of around 1.9 meters (6.2 ft.).Evolution of dark skin, which is linked to the loss of body hair in human ancestors, is complete by 1.2 Ma. Homo pekinensis first appears in Asia around 700 Ka but according to the theory of a recent African origin of modern humans, they could not be human ancestors, but rather, were just a cousin offshoot species from Homo ergaster. Homo heidelbergensis was a very large hominid that had a more advanced complement of cutting tools and may have hunted big game such as horses.

1.2   Ma

Homo antecessor may be a common ancestor of humans and Neanderthals. At present estimate, humans have approximately 20,000–25,000 genes and share 99% of their DNA with the now extinct Neanderthal and 95-99% of their DNA with their closest living evolutionary relative, the chimpanzees.The human variant of the FOXP2 gene (linked to the control of speech) has been found to be identical in Neanderthals. It can therefore be deduced that   Homo antecessor would also have had the human FOXP2 gene.
600 ka A reconstruction of Homo heidelbergensis Three 1.5 m (5 ft.) tall Homo heidelbergensis left footprints in powdery volcanic ash solidified in Italy.  Homo heidelbergensis may be a common ancestor of humans and Neanderthals. It is morphologically very similar to Homo erectus but Homo heidelbergensis had a larger brain-case, about 93% the size of that of Homo sapiens. The holotype of the species was tall, 1.8 m (6 ft.) and more muscular than modern humans.Beginning of the Middle Paleolithic.
338 ka Y-chromosomal Adam lived in Africa approximately 338,000 years ago, according to a recent study. He is the most recent common ancestor from whom all male human Y chromosomes are descended.

200   ka

Homo sapiens sapiensOmo1, Omo2 (Ethiopia, Omo river) are the earliest fossil evidence for anatomically modern Homo sapiens.

160   ka

Homo sapiens (Homo sapiens idaltu) in Ethiopia, Awash River, Herto village, practice mortuary rituals and butcher hippos. Potential earliest evidence of anatomical and behavioral modernity consistent with the continuity hypothesis including use of red ochre and fishing.

150   ka

Mitochondrial Eve is a woman who lived in East Africa. She is the most   recent female ancestor common to all mitochondrial lineages in humans alive today. Note that there is no evidence of any characteristic or genetic drift that significantly differentiated her from the contemporary social group she lived with at the time. Her ancestors were homo sapiens as were her contemporaries.

90   ka

Appearance of mitochondrial haplogroup L2.

70   ka

Behavioral Modernity occurs according to the “great leap forward” theory. This  involves the ability of modern humans to think more conceptually and  symbolically. The use of symbols as messages results in the creation of social   meaning. Such meaning derived is ascribed to social interaction with others. One person makes a gesture, and a second person reacts to that gesture. Then, from that exchange, there is a result that creates a new social reality. In  my opinion this is the beginning of cultural evolution right alongside  biological evolution. It is the start of a meaningful exchange of ideas and  learning.

60   ka

Appearance of mitochondrial haplogroups M and N, which participate in the migration out of Africa. Homo sapiens that leave Africa in this wave start interbreeding with the Neanderthals they encounter.

50   ka

Migration to South Asia. M168 mutation (carried by all non-African males). Beginning of the Upper Paleolithic. mt-haplogroups U,K.

40   ka

Migration to Australia and Europe (Cro-Magnon).

25   ka

The independent Neanderthal lineage dies out.   Y-Haplogroup R2; mt-haplogroups J,X.

12 ka

Beginning of the Mesolithic / Holocene. Y-Haplogroup R1a; mt-haplogroups V,T. Evolution of light skin in Europeans (SLC24A5). Homo floresiencis dies out, leaving Homo sapiens as the only living species of the genus Homo.

Relevance of Research Findings

    As the late Howard Cosell used to say, “Tell it…like…it…is!”

Let me preface this section by sayingmodern human beings, as a species, have a terrible ego problem that has been reinforced by culture for more than two thousand years. The ego problem itself is that mankind sees himself as superior to all other species on earth. This biased misreading of reality all came about because of religion and other aspects of culture.

Although all religions differ in their precepts, all peoples of the world prey on all other animal species, and they often prey on their own species. In the Christian religion, with its “man being made in the image of a god” or all the “having dominion over the animals”, this religion has influenced, both followers and non-followers alike, to accept the idea that mankind is ordained by God to often kill or at least dominate and control all other species on earth. These self-appointed privileges have inculcated in mankind a very inflated (control freak) ego.

All species, of course, have their own particular survival strengths and weaknesses; Mankind is no exception. We have a larger brain (and we even sometimes use it) but we are inferior to the Eagle in eyesight, we can’t fly like a bird, outrun lions, tigers or bears, oh no! Nor, can humans out swim a shark in the ocean, crocodiles in a jungle river, or win a wrestling match with a gorilla. Now that we have that straight, let’s discuss the relevance of evolutionary research.

So, what is the relevance of all the research findings on evolution since Charles Darwin?

First, all the research forms a convergence of the evidence that points to the conclusion that— mankind did in fact descend from the Great Apes (Gorillas, Chimpanzees and bonobos, and Orangutans). Hominids are the first early humans,

Of these our DNA is closest in proximity to the Chimpanzee—where 94% of our genes are identical. Approximately four million years ago, we branched off and became the hominid Australopithecus.

This convergence of the evidence is based on 150+ years of research evidence, data analysis, interpretation, logic, and reason. Add to this scenario the fact that the data on evolution is supported and expanded across 20+ different scientific disciplines. Coupled with this is all the knowledge that has been obtained on evolution going back to the Archean Eon (3.2 – 2.5 billion years ago) when Prokaryotes first evolved (in the oceans). Evolution is no longer regarded as a theory—it is fact.

Second, science in general has served as a catalyst for changing society, and it has succeeded in doing just that. Science in general, as well as paleontology in particular, is fact-based rather than based on superstitious nonsense or supernaturalism. People have benefitted by living in a world where society values truth (albeit still subject to an ongoing process of revision as new evidence is revealed). After all, there are no absolute truths; they don’t exist. What does exist is the fact that “Truth” is what we agree it is. And, informed truth through data and facts is what science is all about.

Thirdly, knowing where one comes from (how we got here) helps one better understand modern society and the relationships between and within different cultures. I posed an important question during Part I of this series. I hope you will go back to Part I and review it once again. I also refer you to Appendix A at the end of Part I to see the entire development of living organisms starting at approximately 3.2 billion years ago. Talk about relevance—what could be more relevant than that?

How to discover your own journey

This is simple. Go to www.genographic.com to order your kit online which has a quick start guide and consent form. Dr. Spencer Wells, the leading scientist of the Geno 2.0 project with National Geographic has said,” The greatest history book ever written is the one hidden in our DNA.” The project will collect DNA samples from your cheeks with enclosed swabs (Don’t worry, it’s painless.) You will then read and complete the consent form and mail it along with your cheek-swab samples in the envelope provided. Following this you can track your results and receive project updates by registering online at www.genographic.com. In about 6 weeks you will receive your detailed results.

You will receive the migration paths your ancient ancestors followed thousands of years ago, and learn the details of your ancestral makeup—your branches on the human family tree. Geno 2 will run a comprehensive analysis to identify thousands of genetic markers on your mitochondrial DNA, which is passed down each generation from mother to child, to reveal your direct maternal deep ancestry. In the case of men, they will also examine markers on the Y chromosome, which is passed down from father to son, to reveal one’s direct paternal deep ancestry.

In addition, for all participants, a collection of more than 130,000 other markers from across your entire genome will reveal the regional affiliations of your ancestry, offering insights into your ancestors who are not on a direct maternal or paternal line.

Included in these markers is a subject that scientists have recently determined to be from our hominid cousins. Neanderthals and the newly discovered Denisovans split from our lineage around 500,000 years ago. As modern humans were first migrating out of Africa more than 60,000 years ago, Neanderthals and Denisovans were still alive and well in Eurasia. It seems that our ancestors met, leaving a small genetic trace of these ancient relatives in our DNA.

My Journey out of Africa.

Specific Details   

Back in January, 2013 I received in the mail the Geno 2 kit. My wife gave me this gift during Christmas by ordering it on the Internet from National Geographic. I filled out the consent form and returned in the mail the two cheek swabs I had used to capture my DNA. The results of my Genographic Project test reveal information about my distant ancestors, including how and when they moved out of Africa and the various populations they interacted with over thousands of years of migration.

How did they do this?

They tracked markers—random, naturally occurring, changes in my DNA. The mutations act as a beacon and can be mapped over thousands of years (on the Y-chromosome for paternal lines and mitochondrial DNA for maternal lines). When geneticists identify such a marker, they try to figure out when it first occurred, and in which geographic region of the world.

In the report below, you will see the group with which I share genetic markers on my maternal and paternal sides. This is called your “haplogroup,” and is expressed in numbers and letters. Be advised as you read this material that much of it is likely to apply to you as well.

Maternal Line—Overview

U5a2a1d (my maternal haplogroup)

The maternal side of my story begins in East Africa around 180,000 years ago.  It was then that the direct maternal ancestor common to all women alive today was born. Of all the woman alive at the time, hers is the only line to survive into current generations.

From East Africa, my ancestors spread across Africa and eventually (between 60 and 70 thousand years ago) made their way to West Asia. It is quite possible that your family story begins this way as well.

My ancestors were content to stay in West Asia for about 44,000 years.  Then, following the food, climate, and opportunities, some of my descendants began to spread toward Europe, crossing through the Caucasus region. . Other members of this branch returned back toward Africa and the Levant region of the Arabian Peninsula. Your family story may continue with either group of travelers

Paternal Line—Overview

R-CTS4299 (my paternal haplogroup)

The paternal side of my story begins around 140,000 years ago, again in Africa. Although there were other human males alive at that time, only one male’s lineage is present in current generations.  Most men, including myself can trace their ancestry to one of this man’s descendants.

In a similar pattern to my maternal side, my ancestors traveled to West Asia where they lived by hunting wildlife and gathering wild fruits and berries. Eventually the paternal groups began spreading out west toward Europe and east to Central Asia.  Some returned to Africa and south into the Levant region.

Detail

The next section of this blog will describe the Maternal Line in more detail.  The Paternal line follows a similar pattern but involves many more groups known as markers.  Therefore, I will save the discussion on the paternal line for a later time.

Maternal Line—Specifics

My Haploid Branch, U5A, began its journey from the original lineage known as L.  This lineage started 180,000 years ago with “Mitochondrial Eve”.  Mitochondrial Eve is the name given to the woman from which all living people today originated.  Eve produced two lineal branches with different sets of genetic mutations.  These branches are known as L0 and L1’2’3’4’5’.  Eventually, L1’2’3’4’5’6 group mutated to a new group called L3.  This group was the first group to leave Africa.  The L3 group which left Africa gave rise to two new haplogroups that populated the rest of the world.

One of those new haplogroups, haplogroup N is present in my descendants. About 60,000 years ago, this group moved north across the Sinai Peninsula, into present day Egypt and north to the eastern Mediterranean regions and western Asia. Descendants of haplogroup N also comprise the most frequent lineage groups found in Europe.

Interestingly, excavations in Israel’s Kebara Cave discovered Neanderthal skeletons that were approximately 60,000 years old. My descendants probably interacted with the Neanderthal hominids explaining the presences of Neanderthal DNA in my DNA.

Before heading into eastern Mediterranean regions and western Asia, some members of haplogroup N mutated into a new haplogroup R. At about 50,000 years ago, this new haplogroup, R, explored new territories. Along with their contemporaries of group N, some returned to northern Africa while others went east into Turkey, Georgia and southern Russia. Still others headed further east into Central Asia. Your story may continue with either the R group or the original N group.  Both groups migrated throughout the world

Somewhere around 47000 years ago, a woman gave rise to the haplogroup U. The haplogroup U is a diverse group.  They have found this group in descendants from Europe, northern Africa, India, Arabia, the northern Caucasus Mountains, and through the Near East.

One of the haplogroup U headed north into Scandinavia.  This group, known as U5 is estimated to be around 30,000 years old.

Around 6,000 to 12,000 years ago, some members of the U5 group left Scandinavia for Western Europe, while others moved further north and east to South Asia. This branch known as U5A has its highest frequencies in Europe, Slovenia, Bulgaria, and Luxembourg.  It is this group that my ancestors probably came from.  However, this group also exists in the Lebanon, India and Ashkenazi Jewish populations.

Because of the complexities and variations of this haplogroup, research is continuing.

Summary of my results

After a detailed analysis of the markers in my paternal DNA and mitochondrial DNA and a comparison to the geographical presence of other human populations with similar markers, the Geno-2 project team concluded that I am 42 % Northern European, 38% Mediterranean and 19% Southwest Asian.

Their analysis explains that the 42% Northern European is a reflection of the fact that:

“This component of your ancestry is found at highest frequency in northern European populations—people from the UK, Denmark, Finland, Russia and Germany in our reference populations. While not limited to these groups, it is found at lower frequencies throughout the rest of Europe. This component is likely the signal of the earliest hunter-gatherer inhabitants of Europe, who were the last to make the transition to agriculture as it moved in from the Middle East during the Neolithic period around 8,000 years ago.”

The 38% Mediterranean is because:

“This component of your ancestry is found at highest frequencies in southern Europe and the Levant—people from Sardinia, Italy, Greece, Lebanon, Egypt and Tunisia in our reference populations. While not limited to these groups, it is found at lower frequencies throughout the rest of Europe, the Middle East, Central and South Asia. This component is likely the signal of the Neolithic population expansion from the Middle East, beginning around 8,000 years ago, likely from the western part of the Fertile Crescent. “

And the 19% Southwest Asian is due to:

“This component of your ancestry is found at highest frequencies in India and neighboring populations, including Tajikistan and Iran in our reference dataset. It is also found at lower frequencies in Europe and North Africa. As with the Mediterranean component, it was likely spread during the Neolithic expansion, perhaps from the eastern part of the Fertile Crescent. Individuals with heavy European influence in their ancestry will show traces of this because all Europeans have mixed with people from Southwest Asia over tens of thousands of years.”

What the Results Mean

The information below is taken directly from the report provided to me by the National Geographic Geno-2 project after their analysis of my DNA.

“Modern day indigenous populations around the world carry particular blends of these regions. We compared your DNA results to the reference populations we currently have in our database and estimated which of these were most similar to you in terms of the genetic markers you carry. This doesn’t necessarily mean that you belong to these groups or are directly from these regions, but that these groups were a similar genetic match and can be used as a guide to help determine why you have a certain result. Remember, this is a mixture of both recent (past six generations) and ancient patterns established over thousands of years, so you may see surprising regional percentages. Read each of the population descriptions below to better interpret your particular result.

 

My first reference population: German

This reference population is based on samples collected from people native to Germany. The dominant 46% Northern European component likely reflects the earliest settlers in Europe, hunter-gatherers who arrived there more than 35,000 years ago. The 36% Mediterranean and 17% Southwest Asian percentages probably arrived later, with the spread of agriculture from the Fertile Crescent in the Middle East over the past 10,000 years. As these early farmers moved into Europe, they spread their genetic patterns as well. Today, northern and central European populations retain links to both the earliest Europeans and these later migrants from the Middle East.”

Reference   Population My   Percentages
German:
Northern   European 46 42
Mediterranean 36 38
Southwest   Asian 17 19

My second reference population: Greek

“This reference population is based on samples collected from the native population of Greece. The 54% Mediterranean and 17% Southwest Asian percentages reflect the strong influence of agriculturalists from the Fertile Crescent in the Middle East, who arrived here more than 8,000 years ago.

The 28% Northern European component likely comes from the pre-agricultural population of Europe—the earliest settlers, who arrived more than 35,000 years ago during the Upper Paleolithic period.

Today, this component predominates in northern European populations, while the Mediterranean component is more common in southern Europe.”

Reference   Population My   Percentages
Greek:
Mediterranean 54 42
Northern   European 28 38
Southwest   Asian 17 19

More Information:

If you want more information the National Geographic Society suggests the following references on their project:

My hominid ancestry

“When our ancestors first migrated out of Africa around 60,000 years ago, they were not alone. At that time, at least two other species of hominid cousins walked the Eurasian landmass: Neanderthals and Denisovans. Most non-Africans are about 2% Neanderthal.”

The Denisovan component of your Geno 2.0 results is more experimental, as we are still working to determine the best way to assess the percentage Denisovan ancestry you carry. The evolution of this data is another way you are actively involved in helping advance knowledge of anthropological genetics!”

My DNA revealed that I am 1.3% Neanderthal.

 

Post Script

Evolution is the real story of our origins. I hope you decide to become involved with National Geographic’s Geno-2 project. As a child I was told that we mostly came from England and Wales. My father’s father was as a jeweler who helped create the Crown Jewels of England. In addition, I was told that the family had Jewish roots many generations earlier, and about a grandmother who spoke French. Being a many generation American, there is some history of being related to Cherokee Indians. My mother’s family had roots in Oklahoma and settlements from Gainesville, Ohio. This is my oral history passed down during the last six generations. Is this oral history true? I don’t know; some of it might have been embellished. Yet, in 1957 a close relative who worked for the Smithsonian Museum (He was a scientist and Curator of Ferns) in Washington D.C., researched our maternal family tree. Much of what I was told as a child was actually true.  No DNA analysis just good documented tracking. If you combine family oral history with the Geno-2 project you probably will possess an interesting picture of your ancestral past (distant and more recent).

Good luck in what you find out about your own journey out of Africa.

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